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2012 Vol. 34, No. 7
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2012, 34(7): 1525-1530.
doi: 10.3724/SP.J.1146.2011.01191
Abstract:
The Kernel Partial Least Squares (KPLS) method has a large calculation since it uses all the principal components for each image block. To consider reconstruction quality and time efficiency, a weighted Boosting based algorithm is proposed in this paper. To choose adaptively the best number of principal components for each image block, the estimator in KPLS prediction model is performed for compensation. The weight coefficient expression of compensation is deduced. The reconstruction effects in different Boosting threshold are discussed. With an appropriate threshold, the chosen best number of principal components can better satisfy KPLS regression model accuracy. Experimental results demonstrate that the proposed method outperforms the conventional methods in super-resolution reconstructed quality.
The Kernel Partial Least Squares (KPLS) method has a large calculation since it uses all the principal components for each image block. To consider reconstruction quality and time efficiency, a weighted Boosting based algorithm is proposed in this paper. To choose adaptively the best number of principal components for each image block, the estimator in KPLS prediction model is performed for compensation. The weight coefficient expression of compensation is deduced. The reconstruction effects in different Boosting threshold are discussed. With an appropriate threshold, the chosen best number of principal components can better satisfy KPLS regression model accuracy. Experimental results demonstrate that the proposed method outperforms the conventional methods in super-resolution reconstructed quality.
2012, 34(7): 1531-1537.
doi: 10.3724/SP.J.1146.2011.01109
Abstract:
This paper proposes a novel model based on the hierarchical representation using heterogeneous descriptors for multi-class generic object detection in real-world scenario. Following the idea of part-based object detection, the model extracts complementary features of object class at different levels and represents them with a unified Conditional Random Field (CRF) framework, in which the individual part and its local features correspond to a unary node and the interactions (edges) between pairwise nodes reflect the underlying geometrical structure of the object class. To improve the discrimination and flexibility of the proposed model, Support Vector Machine (SVM) classifier and the learning of edge structure are combined into CRF according to the geometrical topology of object class. Experimental results on UIUC multi-scale dataset and PASCAL VOC 2007 dataset show that the proposed model can not only effectively represent a variety of complex object classes, also successfully detect objects with pose, scale, illumination variations as well as partial occlusions.
This paper proposes a novel model based on the hierarchical representation using heterogeneous descriptors for multi-class generic object detection in real-world scenario. Following the idea of part-based object detection, the model extracts complementary features of object class at different levels and represents them with a unified Conditional Random Field (CRF) framework, in which the individual part and its local features correspond to a unary node and the interactions (edges) between pairwise nodes reflect the underlying geometrical structure of the object class. To improve the discrimination and flexibility of the proposed model, Support Vector Machine (SVM) classifier and the learning of edge structure are combined into CRF according to the geometrical topology of object class. Experimental results on UIUC multi-scale dataset and PASCAL VOC 2007 dataset show that the proposed model can not only effectively represent a variety of complex object classes, also successfully detect objects with pose, scale, illumination variations as well as partial occlusions.
2012, 34(7): 1538-1542.
doi: 10.3724/SP.J.1146.2011.01269
Abstract:
Global motion estimation based on motion vector field has lower complexity than pixel-based method, so it is widely used in video segmentation and compression. However, outlier motion vectors, caused by image noise or foreground objects, reduce the accuracy of motion vector-based global motion estimation. In this paper, a global motion estimation algorithm based on the motion vector multi-stage processing is proposed to improve the estimation accuracy. The proposed method adaptively removes foreground objects by comparing the motion characteristics differences between the local motion and global motion area. For each block considered, the motion similarity between the neighboring blocks is exploited to detect the cycle smooth area. The isolated noise area is also filtered out. Finally, the inlier motion vectors are used to estimate the global motion parameters. Experimental results show that the proposed scheme filters effectively outlier motion vectors and improves the accuracy of global motion estimation.
Global motion estimation based on motion vector field has lower complexity than pixel-based method, so it is widely used in video segmentation and compression. However, outlier motion vectors, caused by image noise or foreground objects, reduce the accuracy of motion vector-based global motion estimation. In this paper, a global motion estimation algorithm based on the motion vector multi-stage processing is proposed to improve the estimation accuracy. The proposed method adaptively removes foreground objects by comparing the motion characteristics differences between the local motion and global motion area. For each block considered, the motion similarity between the neighboring blocks is exploited to detect the cycle smooth area. The isolated noise area is also filtered out. Finally, the inlier motion vectors are used to estimate the global motion parameters. Experimental results show that the proposed scheme filters effectively outlier motion vectors and improves the accuracy of global motion estimation.
2012, 34(7): 1543-1546.
doi: 10.3724/SP.J.1146.2011.01275
Abstract:
A novel effective image interpolation mechanism to enhance the enlarged image edges is proposed for the visual artifacts problem in traditional magnification methods and the high computational cost in some adaptive image interpolation methods. The proposed algorithm combines the edge-directed smoothness filter with the bilinear interpolation algorithm to obtain the higher quality of an interpolated image both in the edges and smooth areas. The simulation results show that the proposed algorithm gets a better visual effect. Compared with the edge-adaptive interpolation algorithm using covariance, the proposed algorithm is less complex with running time reduced 8.33 s on average and compared with the bi-cubic algorithm has higher quality with the PSNR is raised 0.30 dB on average.
A novel effective image interpolation mechanism to enhance the enlarged image edges is proposed for the visual artifacts problem in traditional magnification methods and the high computational cost in some adaptive image interpolation methods. The proposed algorithm combines the edge-directed smoothness filter with the bilinear interpolation algorithm to obtain the higher quality of an interpolated image both in the edges and smooth areas. The simulation results show that the proposed algorithm gets a better visual effect. Compared with the edge-adaptive interpolation algorithm using covariance, the proposed algorithm is less complex with running time reduced 8.33 s on average and compared with the bi-cubic algorithm has higher quality with the PSNR is raised 0.30 dB on average.
Spectrum Sensing Algorithm Based on Minimum Description Length Criterion for Sparse Multiband Signal
2012, 34(7): 1547-1551.
doi: 10.3724/SP.J.1146.2011.01324
Abstract:
Spectrum sensing issue for sparse multiband signals is considered in this paper. Firstly, undersampling at sub-Nyquist rate are used to construct correlation matrix, and eigenvalue decomposition is carried out. Then, the method uses Minimum Description Length (MDL) criterion to distinguish between signal subspace and noise subspace and finds the spectral support. A spectrum sensing algorithm for sparse multiband signal is presented. Traditional methods distinguish between signal subspace and noise subspace by setting threshold, and make mistake when the threshold is wrong. Adaptability of this algorithm is better because there is no need to set threshold. The simulation results verify the validity of this algorithm.
Spectrum sensing issue for sparse multiband signals is considered in this paper. Firstly, undersampling at sub-Nyquist rate are used to construct correlation matrix, and eigenvalue decomposition is carried out. Then, the method uses Minimum Description Length (MDL) criterion to distinguish between signal subspace and noise subspace and finds the spectral support. A spectrum sensing algorithm for sparse multiband signal is presented. Traditional methods distinguish between signal subspace and noise subspace by setting threshold, and make mistake when the threshold is wrong. Adaptability of this algorithm is better because there is no need to set threshold. The simulation results verify the validity of this algorithm.
2012, 34(7): 1552-1557.
doi: 10.3724/SP.J.1146.2011.01259
Abstract:
Most of the spatial spectrum estimation algorithms fail when the number of targets is lager than the array freedom. To deal with this problem, a spatial filtering method, which is based on steering vector transformation by using the method of interpolated array, is proposed in this paper. The entire observation space is divided into several sub-spaces, and the number of targets in each sub-space is guaranteed smaller than the array freedom by the priori information. By array interpolating, the steering vector of the entire observation is transformed into sub-space steering vector, which means the targets outside the subspace are inhibited. As the result, the mass targets DOA estimation issue in the entire observation space is transformed into a conventional DOA estimation issue in several sub-spaces. Simulative results show the effectiveness of the method presented.
Most of the spatial spectrum estimation algorithms fail when the number of targets is lager than the array freedom. To deal with this problem, a spatial filtering method, which is based on steering vector transformation by using the method of interpolated array, is proposed in this paper. The entire observation space is divided into several sub-spaces, and the number of targets in each sub-space is guaranteed smaller than the array freedom by the priori information. By array interpolating, the steering vector of the entire observation is transformed into sub-space steering vector, which means the targets outside the subspace are inhibited. As the result, the mass targets DOA estimation issue in the entire observation space is transformed into a conventional DOA estimation issue in several sub-spaces. Simulative results show the effectiveness of the method presented.
2012, 34(7): 1558-1561.
doi: 10.3724/SP.J.1146.2011.01167
Abstract:
Based on the theory of electromagnetics, the mutual coupling matrix model between the elements of an electromagnetic vector sensor is put forward in this paper. Using one reference signal source and according the subspace theory, the coupled array manifold is obtained. According the relation between the coupled and the uncoupled array manifolds and by matrix operations, the least squares solution of normalized coupling matrix is obtained. The whole array is calibrated by array elements being calibrated one by one. Finally, the simulation results demonstrate that this approach is correct and effective.
Based on the theory of electromagnetics, the mutual coupling matrix model between the elements of an electromagnetic vector sensor is put forward in this paper. Using one reference signal source and according the subspace theory, the coupled array manifold is obtained. According the relation between the coupled and the uncoupled array manifolds and by matrix operations, the least squares solution of normalized coupling matrix is obtained. The whole array is calibrated by array elements being calibrated one by one. Finally, the simulation results demonstrate that this approach is correct and effective.
2012, 34(7): 1562-1567.
doi: 10.3724/SP.J.1146.2011.01312
Abstract:
The spectral components of speech are usually assumed to be independent in traditional short-time spectrum estimation, which is not the case in practice. To solve this problem, a new speech enhancement algorithm with multivariate Laplace speech model is proposed in this paper. Firstly, the speech Discrete Cosine Transform (DCT) coefficients are modeled by a multivariate Laplace distribution, so the correlations between speech spectral components can be exploited. And then a Minimum-Mean-Square-Error (MMSE) estimator based on the proposed model is derived using a Gaussian scale mixture representation of random vectors. Furthermore, the speech presence uncertainty with the new model is derived to modify the MMSE estimator. Experimental results show that the developed method has better noise suppression performance and lower speech distortion compared to the traditional speech enhancement method.
The spectral components of speech are usually assumed to be independent in traditional short-time spectrum estimation, which is not the case in practice. To solve this problem, a new speech enhancement algorithm with multivariate Laplace speech model is proposed in this paper. Firstly, the speech Discrete Cosine Transform (DCT) coefficients are modeled by a multivariate Laplace distribution, so the correlations between speech spectral components can be exploited. And then a Minimum-Mean-Square-Error (MMSE) estimator based on the proposed model is derived using a Gaussian scale mixture representation of random vectors. Furthermore, the speech presence uncertainty with the new model is derived to modify the MMSE estimator. Experimental results show that the developed method has better noise suppression performance and lower speech distortion compared to the traditional speech enhancement method.
2012, 34(7): 1568-1573.
doi: 10.3724/SP.J.1146.2011.01184
Abstract:
There are two problems in three-dimensional architecture multi-baseline SAR tomography, the hybrid baseline and the non-uniform baseline. To solve the hybrid baseline problem, this article analyzes and deduces the formula to calculate the impact of hybrid baseline on interferometric phase differences between different scatters for the first time. According to their structures, different compensatory approaches are adopted. For the non-uniform baseline problem, a new method named frequency domain least squares Amplitude and Phase EStimation (APES) is proposed, realizing focusing in the height direction with non-uniform data. The results of simulations and the ALOS data prove the effectiveness of the proposed method.
There are two problems in three-dimensional architecture multi-baseline SAR tomography, the hybrid baseline and the non-uniform baseline. To solve the hybrid baseline problem, this article analyzes and deduces the formula to calculate the impact of hybrid baseline on interferometric phase differences between different scatters for the first time. According to their structures, different compensatory approaches are adopted. For the non-uniform baseline problem, a new method named frequency domain least squares Amplitude and Phase EStimation (APES) is proposed, realizing focusing in the height direction with non-uniform data. The results of simulations and the ALOS data prove the effectiveness of the proposed method.
2012, 34(7): 1574-1580.
doi: 10.3724/SP.J.1146.2011.01113
Abstract:
The configuration of the Multiple-Input Multiple-Output (MIMO) array is a good choice for a sparse aperture array for Ultra-WideBand (UWB) through the wall imaging radar. According to the imaging model, an equivalent array for UWB MIMO antenna arrary is analyzed and a design approach for UWB MIMO arrary based on the principle of spatial convolution is given. Simulation results demostrate the effectiveness of the design approach and the feasibility of its application to through-the-wall imaging system. In addition, an adaptive imaging method using coherent coefficient weighting robust Capon beamforming is proposed. Both the theoretical analysis and the experimental results show that the proposed method can achieve high resolution and signal-to-noise ratio in the image.
The configuration of the Multiple-Input Multiple-Output (MIMO) array is a good choice for a sparse aperture array for Ultra-WideBand (UWB) through the wall imaging radar. According to the imaging model, an equivalent array for UWB MIMO antenna arrary is analyzed and a design approach for UWB MIMO arrary based on the principle of spatial convolution is given. Simulation results demostrate the effectiveness of the design approach and the feasibility of its application to through-the-wall imaging system. In addition, an adaptive imaging method using coherent coefficient weighting robust Capon beamforming is proposed. Both the theoretical analysis and the experimental results show that the proposed method can achieve high resolution and signal-to-noise ratio in the image.
2012, 34(7): 1581-1588.
doi: 10.3724/SP.J.1146.2011.01365
Abstract:
Airborne three-dimensional SAR uses an antenna array to resolve along height. Then, both the translation and the rotation errors of the plane should be considered. The reasons are that the translation error will result in defocusing along track and the rotation error will lead to phase distortion of signals from different channels. Therefore, the analysis of the motion error of 3-D SAR is much more difficult compared to that of traditional single-channel SAR. In this paper, based on joint multi-channel auto-focusing technology, a motion compensation algorithm is proposed, which can be utilized to estimate not only the translation error but also the rotation error with high accuracy. Hence the motion error would be precisely compensated. Finally, simulation results confirm the validity of the proposed algorithm.
Airborne three-dimensional SAR uses an antenna array to resolve along height. Then, both the translation and the rotation errors of the plane should be considered. The reasons are that the translation error will result in defocusing along track and the rotation error will lead to phase distortion of signals from different channels. Therefore, the analysis of the motion error of 3-D SAR is much more difficult compared to that of traditional single-channel SAR. In this paper, based on joint multi-channel auto-focusing technology, a motion compensation algorithm is proposed, which can be utilized to estimate not only the translation error but also the rotation error with high accuracy. Hence the motion error would be precisely compensated. Finally, simulation results confirm the validity of the proposed algorithm.
2012, 34(7): 1589-1595.
doi: 10.3724/SP.J.1146.2011.01220
Abstract:
In order to obtain high accuracy of high elevation, long baseline structure is normally used for Interference Synthetic Aperture Radar (InSAR) system. The dynamic and high accuracy measurement of long baseline is necessary. In this paper, a method for dynamic measurement for long baseline using single camera and laser rangefinder system based on distance constraint is proposed. It realizes high accuracy measurement by adding the distance equation to single image space resection mode for constraint. The analysis of principle and experiments are carried out in this paper. The errors of position and attitude are less than 1 mm and 60 arc-seconds obtained by this method in about 50 m photography distance. Experiments show the validity of the method.
In order to obtain high accuracy of high elevation, long baseline structure is normally used for Interference Synthetic Aperture Radar (InSAR) system. The dynamic and high accuracy measurement of long baseline is necessary. In this paper, a method for dynamic measurement for long baseline using single camera and laser rangefinder system based on distance constraint is proposed. It realizes high accuracy measurement by adding the distance equation to single image space resection mode for constraint. The analysis of principle and experiments are carried out in this paper. The errors of position and attitude are less than 1 mm and 60 arc-seconds obtained by this method in about 50 m photography distance. Experiments show the validity of the method.
2012, 34(7): 1596-1601.
doi: 10.3724/SP.J.1146.2011.01172
Abstract:
For the huge computational burden of the matched filter utilized in Passive Coherent Location (PCL) system, this paper proposes a PARAllel FACtor (PARAFAC)-based locating method which estimates directly time delay and Doppler offset. To improve the poor estimation accuracy of frequency blind source separation in large delay spread, a new tensor receiver is built to process simultaneously beamforming, time delay and Doppler offset by exploiting the simultaneous diagonalization. The experiments show that the proposed method can gain high estimation accuracy.
For the huge computational burden of the matched filter utilized in Passive Coherent Location (PCL) system, this paper proposes a PARAllel FACtor (PARAFAC)-based locating method which estimates directly time delay and Doppler offset. To improve the poor estimation accuracy of frequency blind source separation in large delay spread, a new tensor receiver is built to process simultaneously beamforming, time delay and Doppler offset by exploiting the simultaneous diagonalization. The experiments show that the proposed method can gain high estimation accuracy.
2012, 34(7): 1602-1608.
doi: 10.3724/SP.J.1146.2011.01080
Abstract:
For the purpose of improving range resolution of SAR system, one of the main technical approaches is to increase the signal bandwidth by means of multi-channel synthesis. Considering the issue of phase mismatch among multi-channels, channel phase error estimation and compensation method based on echo data is proposed in this paper. Firstly, the polynomial model for channel phase error is established and high-order inner-channel error is then estimated and compensated. Secondly, the residual low-order inter-channel phase error is then estimated and compensated in the procedure of multi-channel synthesis. Aiming to optimize the focus effect of compressed pulse, the optimization estimation model for channel phase error is established. According to the actual case of multi-channel synthesis, the method decomposes the procedure of error estimation and compensation and only a few echo data are required for the data process in addition, which results in the advantage of high efficiency and fast convergence speed. The effectiveness is validated by the process and analysis of real eight-channel raw data.
For the purpose of improving range resolution of SAR system, one of the main technical approaches is to increase the signal bandwidth by means of multi-channel synthesis. Considering the issue of phase mismatch among multi-channels, channel phase error estimation and compensation method based on echo data is proposed in this paper. Firstly, the polynomial model for channel phase error is established and high-order inner-channel error is then estimated and compensated. Secondly, the residual low-order inter-channel phase error is then estimated and compensated in the procedure of multi-channel synthesis. Aiming to optimize the focus effect of compressed pulse, the optimization estimation model for channel phase error is established. According to the actual case of multi-channel synthesis, the method decomposes the procedure of error estimation and compensation and only a few echo data are required for the data process in addition, which results in the advantage of high efficiency and fast convergence speed. The effectiveness is validated by the process and analysis of real eight-channel raw data.
2012, 34(7): 1609-1615.
doi: 10.3724/SP.J.1146.2011.01067
Abstract:
Random noise radar executes pulse compression via direct correlation in time domain for target detection. A novel algorithm is proposed based on compressive sensing for random noise radar system. Projection for low dimension data is adopted instead of correlation; Signal reconstruction is used to substitute signal compression; And much computational load is transferred to background processing. In this algorithm, detected targets in scene satisfy the requirement of sparsity peculiarity, and measurement matrix is constructed by selecting the rows of convolution matrix stochastically. Furthermore, two step iterative shrinkage/thresholding algorithm is applied to reconstruct target signals. With elaborate theoretical derivation, the whole processing of this algorithm is presented. Simulation results are provided to show that the algorithm is able to reconstruct targets efficiently with well computational efficiency. Moreover, factors highly influencing on the results are analyzed. In contrast to correlation operation, reconstruction error is significantly reduced and sidelobes are faithfully suppressed. In addition, phase characters of target information are preserved well.
Random noise radar executes pulse compression via direct correlation in time domain for target detection. A novel algorithm is proposed based on compressive sensing for random noise radar system. Projection for low dimension data is adopted instead of correlation; Signal reconstruction is used to substitute signal compression; And much computational load is transferred to background processing. In this algorithm, detected targets in scene satisfy the requirement of sparsity peculiarity, and measurement matrix is constructed by selecting the rows of convolution matrix stochastically. Furthermore, two step iterative shrinkage/thresholding algorithm is applied to reconstruct target signals. With elaborate theoretical derivation, the whole processing of this algorithm is presented. Simulation results are provided to show that the algorithm is able to reconstruct targets efficiently with well computational efficiency. Moreover, factors highly influencing on the results are analyzed. In contrast to correlation operation, reconstruction error is significantly reduced and sidelobes are faithfully suppressed. In addition, phase characters of target information are preserved well.
2012, 34(7): 1616-1622.
doi: 10.3724/SP.J.1146.2012.00211
Abstract:
The covariance matrix structure of clutter plus jamming is analyzed for side-look airborne MIMO radar, and the upper bound on its rank is derived to equal the summation of clutter and jamming rank subtracting the jammer number. According to this, a certain range of jammer number is attained. If the number of jammers is in this range, the clutter plus jamming covariance matrix is full rank for SIMO radar, whereas rank deficiency for MIMO radar. As a result, the performance of SIMO radar deteriorates severely under this condition, however, the performance of MIMO radar is much better, due to sufficient degrees of freedom to suppress clutter and jamming for MIMO radar. The simulations validate the above conclusion.
The covariance matrix structure of clutter plus jamming is analyzed for side-look airborne MIMO radar, and the upper bound on its rank is derived to equal the summation of clutter and jamming rank subtracting the jammer number. According to this, a certain range of jammer number is attained. If the number of jammers is in this range, the clutter plus jamming covariance matrix is full rank for SIMO radar, whereas rank deficiency for MIMO radar. As a result, the performance of SIMO radar deteriorates severely under this condition, however, the performance of MIMO radar is much better, due to sufficient degrees of freedom to suppress clutter and jamming for MIMO radar. The simulations validate the above conclusion.
2012, 34(7): 1623-1629.
doi: 10.3724/SP.J.1146.2011.01367
Abstract:
Moving targets are smeared and defocused in SAR images by the series range walk and azimuth mismatch which are caused by the fast radial velocity, so it is difficult to detect them. A novel detection scheme is proposed via the airborne single-channel SAR data. The dual-channel can be retrieved by desampling the airborne SAR data in the azimuth direction. Stationary targets and the spectrum splitting of moving targets can be eliminated by coherent subtracting of the dual-channel data. Moreover, moving targets amplitude are double. Then, the Dechirp processing and Hough transform can be applied to accumulate the energy of moving targets. As a result, the integration gain is improved significantly. Comparing with the traditional hybrid integration approach, the proposed scheme can eliminate the clutter and collect the energy of moving targets. The effectiveness and superiority of the proposed scheme are demonstrated by the simulated and real data.
Moving targets are smeared and defocused in SAR images by the series range walk and azimuth mismatch which are caused by the fast radial velocity, so it is difficult to detect them. A novel detection scheme is proposed via the airborne single-channel SAR data. The dual-channel can be retrieved by desampling the airborne SAR data in the azimuth direction. Stationary targets and the spectrum splitting of moving targets can be eliminated by coherent subtracting of the dual-channel data. Moreover, moving targets amplitude are double. Then, the Dechirp processing and Hough transform can be applied to accumulate the energy of moving targets. As a result, the integration gain is improved significantly. Comparing with the traditional hybrid integration approach, the proposed scheme can eliminate the clutter and collect the energy of moving targets. The effectiveness and superiority of the proposed scheme are demonstrated by the simulated and real data.
2012, 34(7): 1630-1636.
doi: 10.3724/SP.J.1146.2011.01189
Abstract:
In order to reduce the complex image registration processing for the airborne dual-antenna interferometric Synthetic Aperture Radar (SAR) system, the extended wavenumber domainK auto-registration imaging algorithm in the range is presented. For the mismatch caused by the path difference of two antennas, this algorithm realizes the precision registration of interferometric image in the range by means of high degree polynomial approximation using scaling principle in course of the imaging processing. Finally, through the processing of the simulation data and the X bands real interferometric data, better interferograms are obtained and the validity of the algorithm presented in the paper is proved.
In order to reduce the complex image registration processing for the airborne dual-antenna interferometric Synthetic Aperture Radar (SAR) system, the extended wavenumber domainK auto-registration imaging algorithm in the range is presented. For the mismatch caused by the path difference of two antennas, this algorithm realizes the precision registration of interferometric image in the range by means of high degree polynomial approximation using scaling principle in course of the imaging processing. Finally, through the processing of the simulation data and the X bands real interferometric data, better interferograms are obtained and the validity of the algorithm presented in the paper is proved.
2012, 34(7): 1637-1641.
doi: 10.3724/SP.J.1146.2011.01353
Abstract:
The independent spatial electric field detecting system should be put up in previous measurement. And the system measures mainly one or two directions of the spatial electric field. This paper presents a novel three dimensional spatial electric field measuring system. In the system, three-dimensional electric field sensor is adopted to detect the spatial electric field. Basing on the existing system of the L-band meteorological radar in meteorology department, the platform of measuring the spatial electric field is constructed, which can detect the meteorological information such as temperature, humidity and pressure synchronously. The unique mechanical structure and the novel signal processing unit are implemented in the sensor system. The detector resolution reaches 20 V/m, and the linearity is better than 1% within the range of -30 kV/m to +30 kV/m. The system can detect the three dimensional electric field at the height of 0~15 km, which provides safety guarantee for the aerocraft.
The independent spatial electric field detecting system should be put up in previous measurement. And the system measures mainly one or two directions of the spatial electric field. This paper presents a novel three dimensional spatial electric field measuring system. In the system, three-dimensional electric field sensor is adopted to detect the spatial electric field. Basing on the existing system of the L-band meteorological radar in meteorology department, the platform of measuring the spatial electric field is constructed, which can detect the meteorological information such as temperature, humidity and pressure synchronously. The unique mechanical structure and the novel signal processing unit are implemented in the sensor system. The detector resolution reaches 20 V/m, and the linearity is better than 1% within the range of -30 kV/m to +30 kV/m. The system can detect the three dimensional electric field at the height of 0~15 km, which provides safety guarantee for the aerocraft.
2012, 34(7): 1642-1646.
doi: 10.3724/SP.J.1146.2011.01311
Abstract:
A new approach is presented for blind estimation of linear block codes parameters with noisy data. Firstly, the proposed method exploits the statistical properties of the dual codes and Walsh-Hadamard transform to determine whether a code is belong to dual code or not. Meanwhile, from the principle of 3 standard deviation, a theoretical threshold to distinguish dual codes is induced. Then the code length and synchronization are estimated when the normalized dual space dimension reaches the maximum. Finally, the parity-check matrix is recovered by the dual codes. Computer simulation results show that the proposed method can provide good performance even when the bit error rate is 0.03.
A new approach is presented for blind estimation of linear block codes parameters with noisy data. Firstly, the proposed method exploits the statistical properties of the dual codes and Walsh-Hadamard transform to determine whether a code is belong to dual code or not. Meanwhile, from the principle of 3 standard deviation, a theoretical threshold to distinguish dual codes is induced. Then the code length and synchronization are estimated when the normalized dual space dimension reaches the maximum. Finally, the parity-check matrix is recovered by the dual codes. Computer simulation results show that the proposed method can provide good performance even when the bit error rate is 0.03.
2012, 34(7): 1647-1652.
doi: 10.3724/SP.J.1146.2011.01359
Abstract:
In order to improve the spectral structure of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a random-polar and Modified CP-EBPSK (MCP-EBPSK) with the adjustment coefficient of spectrum shape is proposed. The principle of random-polar modulated MCP-EBPSK is demonstrated, and the theoretical spectrum expression of MCP-EBPSK is given. Meanwhile, digital impacting filters appropriate for demodulation are designed, the block diagram of random-polar modulated MCP-EBPSK communication system without channel code is given, the power spectrum characteristic and demodulation performance of such modulated signals are analyzed and verified, and the demodulation performance of multipath channel is also simulated. Simulation results show that: by the adjustment of spectrum shape, the new modulation method is promising not only in higher spectrum efficiency, but also better in demodulation performance; At present, this system is not suitable for wireless channel, and is hoped to be applied to cable channel firstly.
In order to improve the spectral structure of random-polar modulated Extended Binary Phase Shift Keying with Continuous Phase (CP-EBPSK), a random-polar and Modified CP-EBPSK (MCP-EBPSK) with the adjustment coefficient of spectrum shape is proposed. The principle of random-polar modulated MCP-EBPSK is demonstrated, and the theoretical spectrum expression of MCP-EBPSK is given. Meanwhile, digital impacting filters appropriate for demodulation are designed, the block diagram of random-polar modulated MCP-EBPSK communication system without channel code is given, the power spectrum characteristic and demodulation performance of such modulated signals are analyzed and verified, and the demodulation performance of multipath channel is also simulated. Simulation results show that: by the adjustment of spectrum shape, the new modulation method is promising not only in higher spectrum efficiency, but also better in demodulation performance; At present, this system is not suitable for wireless channel, and is hoped to be applied to cable channel firstly.
2012, 34(7): 1653-1658.
doi: 10.3724/SP.J.1146.2011.01318
Abstract:
This paper proposed a physical layer secrecy coding algorithm using multi-antenna channel characteristics projection in consideration of the existing secrecy coding,s problems, such as channel condition dependence and random sharing. In channel reciprocal Time-Division-Duplex (TDD) system, multi-antenna transmitter estimates the authorized channel characteristics according to the training symbols transmitted by the single-antenna receiver, and then generates the pair of projected vectors through multi-antenna channel characteristics projection.While transmitting weighted vector is randomly selected from the pair of projected vectors symbol-by-symbol, the Hamming distances of wiretapper,s demodulated codewords are radomly confused so that it is hard to decode normally and secure transmission is qualified. Simulation results show that the scheme makes the wiretapper,s BER near approximately 0.5 and the authorized receiver,s BER a level lower than the existing methods of multi-antenna physical layer secure transmission.
This paper proposed a physical layer secrecy coding algorithm using multi-antenna channel characteristics projection in consideration of the existing secrecy coding,s problems, such as channel condition dependence and random sharing. In channel reciprocal Time-Division-Duplex (TDD) system, multi-antenna transmitter estimates the authorized channel characteristics according to the training symbols transmitted by the single-antenna receiver, and then generates the pair of projected vectors through multi-antenna channel characteristics projection.While transmitting weighted vector is randomly selected from the pair of projected vectors symbol-by-symbol, the Hamming distances of wiretapper,s demodulated codewords are radomly confused so that it is hard to decode normally and secure transmission is qualified. Simulation results show that the scheme makes the wiretapper,s BER near approximately 0.5 and the authorized receiver,s BER a level lower than the existing methods of multi-antenna physical layer secure transmission.
2012, 34(7): 1659-1664.
doi: 10.3724/SP.J.1146.2011.00931
Abstract:
This paper proposes an efficient iterative detection algorithm for MIMO systems, based on the Soft Fixed-complexity Sphere Decoder (SFSD). The algorithm updates the soft output of SFSD using the feedback of the decoder, thus obtaining substantial iterative gain. The number of the branch metric calculation is reduced by exploiting the feature of the multi-level bit mapping constellation. The steps of the detection ordering determination and the QR decomposition are combined, in order to reduce the number of matrix inversion operations in the preprocessing stage. Simulation results in the Long Term Evolution (LTE) downlink system show that, the performance of the proposed algorithm approaches very close to that of the Maximum A Posteriori (MAP) detection with much lower complexity.
This paper proposes an efficient iterative detection algorithm for MIMO systems, based on the Soft Fixed-complexity Sphere Decoder (SFSD). The algorithm updates the soft output of SFSD using the feedback of the decoder, thus obtaining substantial iterative gain. The number of the branch metric calculation is reduced by exploiting the feature of the multi-level bit mapping constellation. The steps of the detection ordering determination and the QR decomposition are combined, in order to reduce the number of matrix inversion operations in the preprocessing stage. Simulation results in the Long Term Evolution (LTE) downlink system show that, the performance of the proposed algorithm approaches very close to that of the Maximum A Posteriori (MAP) detection with much lower complexity.
2012, 34(7): 1665-1671.
doi: 10.3724/SP.J.1146.2011.01157
Abstract:
This paper proposes an interference-aware joint resource allocation scheme for relay-enhanced multicell networks with universal frequency reuse and the coexistence of different communication modes. The design of resource allocation is formulated as a non-linear combinatorial optimization issue with the objective of maximizing the overall system throughput, subject to interference and noise impairments, and individual power constraints at both Base Stations (BSs) and Relay Stations (RSs). To reduce the computational complexity, an inter-cell interference-based scheduling algorithm is proposed to address the user and relay pairing issue. Furthermore, a signomial programming-based optimal power allocation algorithm and a suboptimal minimal energy-consumption power allocation algorithm are devised as well. Numerical results indicate that the proposed algorithms approach to the optimal resource allocation, so that the system performance can be significantly improved in terms of network throughput and energy efficiency.
This paper proposes an interference-aware joint resource allocation scheme for relay-enhanced multicell networks with universal frequency reuse and the coexistence of different communication modes. The design of resource allocation is formulated as a non-linear combinatorial optimization issue with the objective of maximizing the overall system throughput, subject to interference and noise impairments, and individual power constraints at both Base Stations (BSs) and Relay Stations (RSs). To reduce the computational complexity, an inter-cell interference-based scheduling algorithm is proposed to address the user and relay pairing issue. Furthermore, a signomial programming-based optimal power allocation algorithm and a suboptimal minimal energy-consumption power allocation algorithm are devised as well. Numerical results indicate that the proposed algorithms approach to the optimal resource allocation, so that the system performance can be significantly improved in terms of network throughput and energy efficiency.
2012, 34(7): 1672-1677.
doi: 10.3724/SP.J.1146.2011.01310
Abstract:
In order to improve the throughput in wireless multicast scenario, a new type inter-group proportional fairness scheme with average block error rate threshold is proposed, which can not only guarantee fair radio resource allocation but also provide better balance between multi-user diversity and the multicast gain. Theoretical analysis and simulation show that the proposed scheme can effectively improve the wireless multicast system throughput subject to constraint on the average error block rate in comparison with the existing approaches.
In order to improve the throughput in wireless multicast scenario, a new type inter-group proportional fairness scheme with average block error rate threshold is proposed, which can not only guarantee fair radio resource allocation but also provide better balance between multi-user diversity and the multicast gain. Theoretical analysis and simulation show that the proposed scheme can effectively improve the wireless multicast system throughput subject to constraint on the average error block rate in comparison with the existing approaches.
2012, 34(7): 1678-1684.
doi: 10.3724/SP.J.1146.2011.01107
Abstract:
An improved error detection method and a novel Error Concealment (EC) algorithm at the decoder for color plus depth formatted stereoscopic video transmission are presented. The encoding mode of the corrupted macroblock is predicted by the adjacent macroblocks and depth information. In the case that the encoding modes of macroblocks around the corrupted one are inconsistent, the encoding mode of the erroneous macroblock is predicted by the adjacent macroblock whose depth value is closest to that of the corrupted one. According to the encoding mode, the corrupted macroblock is reconstructed by intra-view or inter-view correlation. The experimental results show that the proposed EC algorithm provides 0.8-6.0 dB quality improvement of PSNR against the conventional Boundary Matching Algorithm (BMA) and achieves better subjective quality.
An improved error detection method and a novel Error Concealment (EC) algorithm at the decoder for color plus depth formatted stereoscopic video transmission are presented. The encoding mode of the corrupted macroblock is predicted by the adjacent macroblocks and depth information. In the case that the encoding modes of macroblocks around the corrupted one are inconsistent, the encoding mode of the erroneous macroblock is predicted by the adjacent macroblock whose depth value is closest to that of the corrupted one. According to the encoding mode, the corrupted macroblock is reconstructed by intra-view or inter-view correlation. The experimental results show that the proposed EC algorithm provides 0.8-6.0 dB quality improvement of PSNR against the conventional Boundary Matching Algorithm (BMA) and achieves better subjective quality.
2012, 34(7): 1685-1689.
doi: 10.3724/SP.J.1146.2011.01410
Abstract:
Direct Sequence Spread Spectrum (DSSS) provides an effective way for underwater acoustic communication under low Signal-to-Noise Ratio (SNR). However, low SNR will deteriorate the common multi-path mitigation approaches employed in DSSS system such as channel equalizer and rake receiver. Considering that multi-channel time reversal has the ability to refocus the energy in spatial and temporal domain, multi-channel time reversal is incorporated with DSSS technology to suppress the multipath interference under low SNR, also convolutional coding is adopted to further improve the communication performance. Lake trial results show the effectiveness of the proposed scheme.
Direct Sequence Spread Spectrum (DSSS) provides an effective way for underwater acoustic communication under low Signal-to-Noise Ratio (SNR). However, low SNR will deteriorate the common multi-path mitigation approaches employed in DSSS system such as channel equalizer and rake receiver. Considering that multi-channel time reversal has the ability to refocus the energy in spatial and temporal domain, multi-channel time reversal is incorporated with DSSS technology to suppress the multipath interference under low SNR, also convolutional coding is adopted to further improve the communication performance. Lake trial results show the effectiveness of the proposed scheme.
2012, 34(7): 1690-1696.
doi: 10.3724/SP.J.1146.2011.01222
Abstract:
Because buffer is significant for routes and switches energy consumption in network. This paper proposes an energy consumption model of buffer-less self-routing grouping switching. The model with grouping switching fabric constructed by G statistical multiple routing units and Banyan-type exchanges. Based on blocking probability and time delay requirement buffer-less, the number of input/output extensibility and exchange between stages optimal layout are used to save energy. The quantization comparing between buffer energy consumption and buffer-less switching fabric energy consumption based on same network performance shows that: the latter energy consumption is less than the former. The simulation result shows that: the lager parameter G is, the less energy consumption of routing unit is, the less parameter k is, the less energy consumption of routing unit is, and energy consumption of Divide-and-Conquer (DC) exchange between stages is least among Banyan-type switching network.
Because buffer is significant for routes and switches energy consumption in network. This paper proposes an energy consumption model of buffer-less self-routing grouping switching. The model with grouping switching fabric constructed by G statistical multiple routing units and Banyan-type exchanges. Based on blocking probability and time delay requirement buffer-less, the number of input/output extensibility and exchange between stages optimal layout are used to save energy. The quantization comparing between buffer energy consumption and buffer-less switching fabric energy consumption based on same network performance shows that: the latter energy consumption is less than the former. The simulation result shows that: the lager parameter G is, the less energy consumption of routing unit is, the less parameter k is, the less energy consumption of routing unit is, and energy consumption of Divide-and-Conquer (DC) exchange between stages is least among Banyan-type switching network.
2012, 34(7): 1697-1702.
doi: 10.3724/SP.J.1146.2011.01168
Abstract:
A Reputation-based Service Differentiated Incentive (RSDI) mechanism is proposed in this paper to solve the selfish behavior of nodes during consciously supporting services efficiently for Mobile Ad-hoc NETworks (MANETs). With a clustering global reputation model and associating services with reputation using grades, RSDI provides differentiated services based on reputation; The nodes which have higher reputation level can consume higher level services, consuming services or refusing to provide services intentionally will reduce nodes reputation, nodes need positively provide trustworthy services to increase their reputation in order to ensure consuming services. Simulations show that RSDI can resist the selfish behavior of nodes, and motivate nodes to positively provide trustworthy services effectively.
A Reputation-based Service Differentiated Incentive (RSDI) mechanism is proposed in this paper to solve the selfish behavior of nodes during consciously supporting services efficiently for Mobile Ad-hoc NETworks (MANETs). With a clustering global reputation model and associating services with reputation using grades, RSDI provides differentiated services based on reputation; The nodes which have higher reputation level can consume higher level services, consuming services or refusing to provide services intentionally will reduce nodes reputation, nodes need positively provide trustworthy services to increase their reputation in order to ensure consuming services. Simulations show that RSDI can resist the selfish behavior of nodes, and motivate nodes to positively provide trustworthy services effectively.
2012, 34(7): 1703-1708.
doi: 10.3724/SP.J.1146.2011.01293
Abstract:
It is hard to supply high quality service constantly because of the dynamic characteristics of MANET and the limit of devices capacity in ubiquitous environment. In this paper, personal ubiquitous service model is defined and Multi-Devices Cooperation Problem (MDCP) is imported based on service context. And personal multi-devices cooperation mechanism is proposed to support three processes of service requiring, multi-devices cooperation building and quality monitoring. Finally, the simulation is implemented with OPNET and MATLAB. The result shows this mechanism could support personalized services, improve 3%～17% about packet loss rate, save 0%～20% in energy consumption and cut short in the time of service re-start than Dynamic Task-embedding Anycasting (DTA) and Service-oriented Device Anycasting (SDA).
It is hard to supply high quality service constantly because of the dynamic characteristics of MANET and the limit of devices capacity in ubiquitous environment. In this paper, personal ubiquitous service model is defined and Multi-Devices Cooperation Problem (MDCP) is imported based on service context. And personal multi-devices cooperation mechanism is proposed to support three processes of service requiring, multi-devices cooperation building and quality monitoring. Finally, the simulation is implemented with OPNET and MATLAB. The result shows this mechanism could support personalized services, improve 3%～17% about packet loss rate, save 0%～20% in energy consumption and cut short in the time of service re-start than Dynamic Task-embedding Anycasting (DTA) and Service-oriented Device Anycasting (SDA).
2012, 34(7): 1709-1714.
doi: 10.3724/SP.J.1146.2011.01283
Abstract:
Various methods are capable of classifying Peer to Peer (P2P) traffic in coarse grained way efficiently and accurately. However, few papers focus on the fine grained identification of P2P traffic. Affinity Propagation (AP) algorithm is brought to P2P traffic identification field for the first time and a novel method of identifying P2P traffic finely based on Hierarchical Weighted Semi-supervised AP (Hi-WSAP) algorithm is proposed, which is on the foundation of the Hi-WAP algorithm and absorbs the semi-supervised thought. The proposed method identifies P2P traffic in semi-supervised way by application employing only 10 fast computed traffic features. Experimental results using two datasets show this method achieves high identification accuracy and low time complexity, which provides a path to finely identify P2P traffic in real-time.
Various methods are capable of classifying Peer to Peer (P2P) traffic in coarse grained way efficiently and accurately. However, few papers focus on the fine grained identification of P2P traffic. Affinity Propagation (AP) algorithm is brought to P2P traffic identification field for the first time and a novel method of identifying P2P traffic finely based on Hierarchical Weighted Semi-supervised AP (Hi-WSAP) algorithm is proposed, which is on the foundation of the Hi-WAP algorithm and absorbs the semi-supervised thought. The proposed method identifies P2P traffic in semi-supervised way by application employing only 10 fast computed traffic features. Experimental results using two datasets show this method achieves high identification accuracy and low time complexity, which provides a path to finely identify P2P traffic in real-time.
2012, 34(7): 1715-1720.
doi: 10.3724/SP.J.1146.2011.01350
Abstract:
Utilized the multi-homing in IPv6, motivated by the idea of frequency hopping communications, multi- homing hopping conception is proposed which can increase the address search space and difficulty of traffic monitoring for attackers by changing the host node address in multiple address domains dynamically. An active defense model is established based on multi-homing hopping. The double random address generation algorithm is proposed which ensured the IP address of the host scattered in multiple address domains randomly. Two address handoff tactics are proposed which ensure the continuance and efficiency of communication. Host address security and traffic security are analyzed. The performance and function of the proposed model are evaluated empirically. The results show that multi-homing hopping based IPv6 proactive network defense model can effectively enhance the attacker overhead and protect the network.
Utilized the multi-homing in IPv6, motivated by the idea of frequency hopping communications, multi- homing hopping conception is proposed which can increase the address search space and difficulty of traffic monitoring for attackers by changing the host node address in multiple address domains dynamically. An active defense model is established based on multi-homing hopping. The double random address generation algorithm is proposed which ensured the IP address of the host scattered in multiple address domains randomly. Two address handoff tactics are proposed which ensure the continuance and efficiency of communication. Host address security and traffic security are analyzed. The performance and function of the proposed model are evaluated empirically. The results show that multi-homing hopping based IPv6 proactive network defense model can effectively enhance the attacker overhead and protect the network.
2012, 34(7): 1721-1726.
doi: 10.3724/SP.J.1146.2011.01240
Abstract:
A new secure image steganographic algorithm for encrypted domain steganography is proposed based on fully homomorphic encryption and double-layer embedding. The proposed method can reach the capacity of classical steganography while resist to statistical steganalysis both in plaintext domain and encrypted domain. At first, a novel double-layered embedding algorithm based on adaptive steganography and Wet Paper Codes(WPCs) is constructed for plaintext embedding. Then an fully homomorphic encryption algorithm is modified to encrypt the stego image. Finally, the embedding message is extracted in encrypted domain. The performance analysis and experimental results show that the steganographic security of the proposed method preserves well performance under several attacking conditions, including both steganographic/encrypted keys leakage, encrypted keys leakage and no keys leakage.
A new secure image steganographic algorithm for encrypted domain steganography is proposed based on fully homomorphic encryption and double-layer embedding. The proposed method can reach the capacity of classical steganography while resist to statistical steganalysis both in plaintext domain and encrypted domain. At first, a novel double-layered embedding algorithm based on adaptive steganography and Wet Paper Codes(WPCs) is constructed for plaintext embedding. Then an fully homomorphic encryption algorithm is modified to encrypt the stego image. Finally, the embedding message is extracted in encrypted domain. The performance analysis and experimental results show that the steganographic security of the proposed method preserves well performance under several attacking conditions, including both steganographic/encrypted keys leakage, encrypted keys leakage and no keys leakage.
2012, 34(7): 1727-1734.
doi: 10.3724/SP.J.1146.2011.01364
Abstract:
A new single-channel double-color image encryption algorithm is proposed by combining Discrete Fractional Random Transform (DFrRT) with linear congruence theory. The two input RGB images are converted into their indexed image formats, and one of the 2D indexed image is encoded in amplitude part and the other is encoded into the spatial domain phase mask. The two color map matrixes are embedded in the fractional domain phase mask which is generated by Linear Congruential Generator (LCG). The amplitude-phase encoding is introduced into the optical encryption system to implement the double-color image encryption algorithm without increasing other optical elements. The fractional order of DFrRT and the four parameters of the linear function are the keys to enhance the security of the proposed algorithm, and the Mean Square Error (MSE) between the decrypted images and the input ones for all keys are calculated. The performance of the proposed scheme is analyzed against ciphertext-only attack, noise addition and occlusion of the encrypted image, respectively. Numerical simulation results demonstrate the feasibility and effectiveness of the proposed method.
A new single-channel double-color image encryption algorithm is proposed by combining Discrete Fractional Random Transform (DFrRT) with linear congruence theory. The two input RGB images are converted into their indexed image formats, and one of the 2D indexed image is encoded in amplitude part and the other is encoded into the spatial domain phase mask. The two color map matrixes are embedded in the fractional domain phase mask which is generated by Linear Congruential Generator (LCG). The amplitude-phase encoding is introduced into the optical encryption system to implement the double-color image encryption algorithm without increasing other optical elements. The fractional order of DFrRT and the four parameters of the linear function are the keys to enhance the security of the proposed algorithm, and the Mean Square Error (MSE) between the decrypted images and the input ones for all keys are calculated. The performance of the proposed scheme is analyzed against ciphertext-only attack, noise addition and occlusion of the encrypted image, respectively. Numerical simulation results demonstrate the feasibility and effectiveness of the proposed method.
2012, 34(7): 1735-1743.
doi: 10.3724/SP.J.1146.2011.01004
Abstract:
A new image parallel encryption strategy is proposed based on the improved hyperchaotic sequences and ciphertext diffusion in crisscross pattern. Firstly, the hyperchaotic sequences are modified to generate chaotic key stream that is more suitable for image encryption. Secondly, the final key stream is generated by correlating the chaotic key stream and plaintext which result in both key sensitivity and plaintext sensitivity. The plain-image is firstly divided into two sub-images, then sub-images are encrypted simultaneously in a parallel manner with two rounds. The technology of ciphertext diffusion in crisscross pattern is introduced. Performance test and security analysis are performed using key space analysis and algorithm efficiency test, the pixels distribution character, correlation coefficients, the ability to resist differential attack and key sensitivity test. Results suggest that the proposed image encryption scheme is secure and efficient, with high potential to be adopted for the secure image communication applications.
A new image parallel encryption strategy is proposed based on the improved hyperchaotic sequences and ciphertext diffusion in crisscross pattern. Firstly, the hyperchaotic sequences are modified to generate chaotic key stream that is more suitable for image encryption. Secondly, the final key stream is generated by correlating the chaotic key stream and plaintext which result in both key sensitivity and plaintext sensitivity. The plain-image is firstly divided into two sub-images, then sub-images are encrypted simultaneously in a parallel manner with two rounds. The technology of ciphertext diffusion in crisscross pattern is introduced. Performance test and security analysis are performed using key space analysis and algorithm efficiency test, the pixels distribution character, correlation coefficients, the ability to resist differential attack and key sensitivity test. Results suggest that the proposed image encryption scheme is secure and efficient, with high potential to be adopted for the secure image communication applications.
2012, 34(7): 1744-1747.
doi: 10.3724/SP.J.1146.2012.00261
Abstract:
In order to extend visualization of attack graphs, a method of adjacency matrix based on attributes is proposed, and the arithmetic of multi-step adjacency matrix is designed. The elements of the matrix shows connections of the network. The probability of attack paths is obtained through numeration of probability of the adjacency matrix. Experiment results show that the proposed method can efficiently decrease the complexity of attack graphs, and make it easier to analyze the network vulnerability.
In order to extend visualization of attack graphs, a method of adjacency matrix based on attributes is proposed, and the arithmetic of multi-step adjacency matrix is designed. The elements of the matrix shows connections of the network. The probability of attack paths is obtained through numeration of probability of the adjacency matrix. Experiment results show that the proposed method can efficiently decrease the complexity of attack graphs, and make it easier to analyze the network vulnerability.
2012, 34(7): 1748-1754.
doi: 10.3724/SP.J.1146.2011.01150
Abstract:
Infrastructure-as-a-Service (IaaS) frees users from the trouble of self-management of computer hardware, and provides users with anytime, anywhere on demand computing and storage resources. Eucalyptus is an open source IaaS framework implementation which is used for research. However, there is no paper describes how to use all the modules of Eucalyptus to supply security infrastructure service. In accordance with the security requirements of IaaS, a trusted IaaS framework is provided. The framework provides infrastructure service in five steps, and designs protocols which based on Trusted Platform Module (TPM) to achieve these steps. During the designing process, the use of TPM is strictly standardized and trusted third party is concerned in order to restrict the power of service operator. All the protocols pass the security examination of automatic analysis tool-Scyther, so the conclusion that the framework meets the requirements of IaaS is generalized.
Infrastructure-as-a-Service (IaaS) frees users from the trouble of self-management of computer hardware, and provides users with anytime, anywhere on demand computing and storage resources. Eucalyptus is an open source IaaS framework implementation which is used for research. However, there is no paper describes how to use all the modules of Eucalyptus to supply security infrastructure service. In accordance with the security requirements of IaaS, a trusted IaaS framework is provided. The framework provides infrastructure service in five steps, and designs protocols which based on Trusted Platform Module (TPM) to achieve these steps. During the designing process, the use of TPM is strictly standardized and trusted third party is concerned in order to restrict the power of service operator. All the protocols pass the security examination of automatic analysis tool-Scyther, so the conclusion that the framework meets the requirements of IaaS is generalized.
2012, 34(7): 1755-1759.
doi: 10.3724/SP.J.1146.2011.01241
Abstract:
Based on Impedance Boundary Condition (IBC), a Method of Moments-Physical Optics (MoM-PO) hybrid method is proposed for modeling the electromagnetic scattering from three-dimensional (3-D) anisotropic impedance surface. The surface equivalence principle is adopted while the scattering can be replaced by the radiation of surface electromagnetic currents in the MoM-and the PO-region, with the current expanded by 3-D Rao-Wilton-Glisson (RWG) vector basis functions. The simulation of target coated with anisotropic material is performed with the electromagnetic parameters characterized by the surface impedance dyadic, while the numerical results agree well with the exact solutions such as Mie series, which shows the validity of the proposed method.
Based on Impedance Boundary Condition (IBC), a Method of Moments-Physical Optics (MoM-PO) hybrid method is proposed for modeling the electromagnetic scattering from three-dimensional (3-D) anisotropic impedance surface. The surface equivalence principle is adopted while the scattering can be replaced by the radiation of surface electromagnetic currents in the MoM-and the PO-region, with the current expanded by 3-D Rao-Wilton-Glisson (RWG) vector basis functions. The simulation of target coated with anisotropic material is performed with the electromagnetic parameters characterized by the surface impedance dyadic, while the numerical results agree well with the exact solutions such as Mie series, which shows the validity of the proposed method.
2012, 34(7): 1760-1766.
doi: 10.3724/SP.J.1146.2011.01219
Abstract:
Three novel groove-loaded Folded Waveguide Slow-Wave Structures (FWSWS),which include triangle groove-loaded, trapezoid groove-loaded and swallow-tailed groove-loaded FWSWS, are analyzed for the purpose of improving beam-wave interaction. The high-frequency characteristics, including dispersion properties and interaction impedance, are investigated by numerical simulation, and the nonlinear large-signal performances of these Traveling Wave Tubes (TWTs), including output power, gain and electron efficiency, are also analyzed and compared by a 3-D particle-in-cell code MAGIC3D. Within the same beam parameters and input power, it is concluded from the comparison that: among these FWSWSs, the trapezoid groove-loaded FWSWS has the highest output power (255 W), saturated gain (37.1 dB), and electron efficiency (10.7%); The swallow-tailed groove-loaded FWSWS owns the shortest circuit length to obtain the saturated gain of which is 64.2 mm; the triangle groove-loaded FWSWS has the widest bandwidth.
Three novel groove-loaded Folded Waveguide Slow-Wave Structures (FWSWS),which include triangle groove-loaded, trapezoid groove-loaded and swallow-tailed groove-loaded FWSWS, are analyzed for the purpose of improving beam-wave interaction. The high-frequency characteristics, including dispersion properties and interaction impedance, are investigated by numerical simulation, and the nonlinear large-signal performances of these Traveling Wave Tubes (TWTs), including output power, gain and electron efficiency, are also analyzed and compared by a 3-D particle-in-cell code MAGIC3D. Within the same beam parameters and input power, it is concluded from the comparison that: among these FWSWSs, the trapezoid groove-loaded FWSWS has the highest output power (255 W), saturated gain (37.1 dB), and electron efficiency (10.7%); The swallow-tailed groove-loaded FWSWS owns the shortest circuit length to obtain the saturated gain of which is 64.2 mm; the triangle groove-loaded FWSWS has the widest bandwidth.
2012, 34(7): 1767-1772.
doi: 10.3724/SP.J.1146.2011.01298
Abstract:
As a kind of basic operation, polarity conversion is largely involved in the polarity optimization of Reed- Muller (RM) logic circuits, especially for large-scale circuits. The rate of polarity conversion has a direct impact on efficiency of the polarity optimization. A mathematical model is established for area optimization of XNOR/OR circuits, which is a kind of basic realization of RM logic circuits. A novel polarity conversion technique is proposed by combining the superiorities of the existing ones. Based on the features of the novel conversion technique, an area optimization is proposed for large-scale XNOR/OR circuits. Experimental results show that compared to other conversion algorithms, the proposed polarity conversion technique can significantly improve the area optimization of XNOR/OR circuits.
As a kind of basic operation, polarity conversion is largely involved in the polarity optimization of Reed- Muller (RM) logic circuits, especially for large-scale circuits. The rate of polarity conversion has a direct impact on efficiency of the polarity optimization. A mathematical model is established for area optimization of XNOR/OR circuits, which is a kind of basic realization of RM logic circuits. A novel polarity conversion technique is proposed by combining the superiorities of the existing ones. Based on the features of the novel conversion technique, an area optimization is proposed for large-scale XNOR/OR circuits. Experimental results show that compared to other conversion algorithms, the proposed polarity conversion technique can significantly improve the area optimization of XNOR/OR circuits.
2012, 34(7): 1773-1778.
doi: 10.3724/SP.J.1146.2011.01185
Abstract:
Based on the characteristics of current-mode circuits, which can easily realize arithmetic operations, the threshold-arithmetic operation and the nonnegative operation are defined in this paper, and the threshold-arithmetic algebraic system suitable to design current-mode circuits is established. Then, HE map is defined and used as the graphic representation of threshold-arithmetic functions, and the method of converting traditional logic function to threshold-arithmetic function with HE map is expounded. Finally, the design method of current-mode CMOS circuits based on threshold-arithmetic algebraic system and HE map is proposed. The HSPICE simulation results using TSMC 0.18m technology show that the designed current-mode CMOS circuits have the correct logic functions. The threshold-arithmetic algebraic system is a new simple and effective method for designing the current-mode circuits.
Based on the characteristics of current-mode circuits, which can easily realize arithmetic operations, the threshold-arithmetic operation and the nonnegative operation are defined in this paper, and the threshold-arithmetic algebraic system suitable to design current-mode circuits is established. Then, HE map is defined and used as the graphic representation of threshold-arithmetic functions, and the method of converting traditional logic function to threshold-arithmetic function with HE map is expounded. Finally, the design method of current-mode CMOS circuits based on threshold-arithmetic algebraic system and HE map is proposed. The HSPICE simulation results using TSMC 0.18m technology show that the designed current-mode CMOS circuits have the correct logic functions. The threshold-arithmetic algebraic system is a new simple and effective method for designing the current-mode circuits.
